Evansville, IN, USA
N7775L
Mooney M20M
The personal flight impacted terrain in a residential neighborhood about one mile north of the departure airport while executing an emergency return to the airport. The airplane impacted a wooded area in a 20-degree nose down trajectory and came to rest about 142 feet from the initial impact point. The pilot reported smoke in the cockpit 55 seconds after takeoff which was then followed by a report of a fire 32 seconds later. A witness reported seeing gray and black smoke trailing from the right side of the exhaust area. Inspection of the wreckage revealed that the turbocharger exhaust V-band clamp was separated through the band. Metallurgical examination indicated that the separation was consistent with a fatigue fracture. According to maintenance records, the V-band clamp was installed in 1990 in response to a service letter (SL). An airworthiness directive (AD) was then issued in 1991 requiring the replacement of the V-band clamp with one which was of the same part number as called for by the SL. The V-band clamp found in the wreckage of the accident airplane was of the same part number required by the SL and AD. The airplane received an annual inspection 25 days prior to the accident at which time the V-band clamp would have accumulated a total time in service of 1,402 hours. Engine overhauls and exhaust system related maintenance has necessitated the clamp's repeated removal and installation since its original installation. According to the airplane emergency procedures for smoke/fire, the master switch and fuel selector valve are to be selected to the off positions. Radio transmissions by the flight continued after the initial report of smoke. Inspection of the wreckage revealed that the fuel selector valve was selected to the right fuel tank.
HISTORY OF FLIGHT On November 27, 2001, at 1513 central standard time, a Mooney M20M, N7775L, piloted by a private pilot, was destroyed on impact with terrain and fire approximately one mile north of Evansville Regional Airport (EVV), Evansville, Indiana. The flight was returning to EVV after smoke was reported in the cockpit which was then followed by a report of fire at an unspecified location aboard the airplane. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 personal flight was operating on an instrument flight rules flight plan. The pilot and passenger were fatally injured. The flight originated from EVV, at 1512, and was en route to Indianapolis International Airport, Indianapolis, Indiana. The airplane was topped off with fuel prior to departure. A lineman, who was also a aircraft rescue firefighter, stated that he refueled the right wing after the left wing was refueled with 100 low lead aviation fuel by another lineman. The following radio transmissions were recorded between EVV Air Traffic Control Tower and N7775L: At 1502:35, N7775L transmitted, "evansville clearance delivery mooney triple seven five lima." At 1502:40, Evansville Clearance Delivery (CD) transmitted, "mooney triple seven five lima is cleared to indianapolis as filed maintain four thousand expect niner thousand one zero minutes after departure departure frequency one two seven point three five squawk four five two one." At 1502:57, N7775L transmitted, "mooney triple seven five lima is cleared to indianapolis as filed climb and maintain four expect nine in ten minutes one twenty seven therty five and four five two one [sic]." At 1503:07, CD transmitted, "mooney triple seven five lima readback correct contact the tower one one eight point seven when you're ready to taxi." At 1503:13, N7775L transmitted, "thank you sir." At 1503:52, N7775L transmitted, "evansville tower mooney triple seven five lima coming out of tristate." At 1503:58, Evansville Local Control (LC) transmitted, "mooney triple seven five lima evansville tower taxi to runway two ah two seven via taxiway alpha hold short of runway two seven do your runup there and advise when ready." At 1504:11, N7775L transmitted, " *(ah) roger you give me two seven correct." At 1504:14, LC transmitted, "affirmative unless you'd like a different runway." At 1504:17, N7775L transmitted, "oh that's alright thank you." At 1504:25, N7775L transmitted, "i'm not familiar with the airport i guess i go straight ahead here cross this other runway." At 1504:30, LC transmitted, "affirmative taxi straight ahead you’ll cross that ah runway and you’ll hold short of the next intersection that will be two seven." At 1504:37, N7775L transmitted, "thank you sir." At 2104:43, N7775L transmitted, "i didn't get an atis it was i guess they were changing it or something it was off the air." At 2104:48, LC transmitted, "okay ah atis information mike is current wind two seven zero at six altimeter three zero zero six." At 1504:56, N7775L transmitted, "zero zero six seven five lima." At 1509:13, N7775L transmitted, "evansville tower mooney seven five lima is ready to back taxi on two seven." At 1509:24, N7775L transmitted, "hold short of two two seven five lima." At 1509:45, LC transmitted, "mooney seven five lima taxi across runway two two make a one eighty and hold short of ah two two on the east side traffic and a half out a citation." At 1509:54, N7775L transmitted, "(unintelligible) five lima crossing two two ah one eighty and hold short of two two again." At 1511:36, LC transmitted, "mooney ah triple seven five lima fly runway heading runway two seven cleared for take off." At 1511:42, N7775L transmitted, "seven five lima rolling." At 1512:34, LC transmitted, "mooney seven five lima contact evansville departure." At 1512:37, N7755L transmitted, "seven five lima has got some sort of smoke in the cockpit we're coming back in we’ll swing around to two two." At 1512:47, LC transmitted, "seven five lima roger runway two two you're cleared to land wind ah three two zero at five runway nine is available if you want it." At 1512:56, N7775L transmitted, "seven five lima (unintelligible)." At 1513:09, N7775L transmitted, "we've got a fire." There were no further transmissions by N7775L. The lineman/firefighter stated that he saw the airplane flying in an easterly direction approximately 500-1,000 feet above ground level with gray and black smoke trailing from the area of the exhaust on the right side of the airplane. He did not recall seeing the landing gear down or any lights on. The airplane appeared to him as to be flying straight and level for several seconds before he lost sight of it behind a tree line. Seconds after losing sight of the airplane, he saw smoke rise above the tree line. The lineman/firefighter then responded with the emergency vehicles from the EVV Airport Rescue Fire Fighting station. Upon his arrival the largest fire, after the main wreckage was extinguished, was near the pilot seats, instrument panel and rudder controls. PERSONNEL INFORMATION The pilot, age 79, held a private pilot certificate with airplane single-engine land and instrument airplane ratings. A total flight time of 3,605 hours was reported at the issuance of the pilot's third class medical certificate on September 27, 2001. The medical certificate had the following restriction: "must wear corrective lenses." Copies of the pilot's logbook provided to the National Transportation Safety Board showed that he accumulated total flight time of 1,382.3 hours in M20M airplanes as of January 15, 2001. The pilot had no record of any previous accidents, incidents, or violations. AIRCRAFT INFORMATION The 1989 Mooney M20M, serial number 27-0011, was registered with a normal category airworthiness certificate to the pilot's corporation on December 19, 1990, at a total time (TT) of 455 hours. The airplane was last inspected on November 2, 2001, at a TT of 1,857 hours during an annual inspection by a Mooney service center. The maintenance record indicated that all ADs thru 2001-21 were checked at the time of the annual inspection. The airplane was powered by a turbocharged fuel-injected Lycoming TIO-540-AF1A, serial number L-9106-61A, engine rated at 310 horse power and 2,575 rpm. The engine received a top overhaul on February 10, 1997, at a TT of 1,456 hours and a major overhaul on December 22, 1998, at a TT of 1,595 hours. The M20M is equipped with two integral fuel tanks in the forward sections of the wings with a total fuel capacity is 89 gallons. Fuel feeds from either tank to a three position fuel selector valve, located on the floor of the cockpit, thru a gascolator and an electric fuel pump, all of which are located behind the firewall. The fuel selector has the following position selections: left fuel tank, off, and right fuel tank. Mooney Aircraft Corporation (MAC) issued Special Letter (SL) 90-6 on November 1, 1990, for the replacement of the exhaust/turbocharger coupling on Mooney TLS and M20M airplanes with serial numbers 27-0001 thru 27-0071 and 27-0073, 27-0075, 27-0078. The SL states, "There has been a report of the engine tailpipe coupling failing. If this happens there is a possibility that the tailpipe may depart the aircraft and exhaust gas may exit directly onto the firewall causing damage to firewall and components in the immediate area." . It called for the replacement of the exhaust/turbocharger coupling with an Aeroequip V-band clamp, part number 55677-340M or a Textron-Lycoming V-band clamp, part number 40D21162-340M. According to the airplane maintenance record, the turbocharger clamp was inspected and a new clamp installed on December 19, 1990, at an airplane TT of 455 hours. The record made reference to SL 90-6 and listed the clamp as R89446-T, which according to an Aeroequip representative was an Aeroequip work order number. A search for work order R89446-T, undertaken by Aeroequip, was unable to find the work order. Federal regulations require that work orders be retained for three years. There were no additional record entries citing the exhaust/turbocharger coupling or V-band clamp. Airworthiness Directive (AD) 91-03-15, effective February 19, 1991, was issued by the Federal Aviation Administration, to prevent the discharge of high temperature exhaust gases inside the engine compartment that could result in the airplane cabin catching fire. The AD required the replacement of the tailpipe coupling (P/N MVT69183-275, LW-12093-8, 4571-275, 4574-275, or 4391 AF, with an improved tailpipe coupling (P/N 55677-340M or 40D21162-340M) in accordance with MAC SL 90-06. The M20M Service and Maintenance Manual, section 5-10-01, lists the recommended overhaul or replacement time limits of V-band couplings and gaskets to be accomplished at engine overhaul or on condition. The Lycoming recommended overhaul time for the TIO-540-AF1A is 2,000 hours. On condition items are to be repaired, replaced or overhauled when inspection performance reveals an unserviceable condition. Textron Lycoming Service Instruction 1422A, Exhaust System Inspection, states that at each 50 hour inspection of the exhaust system on all Textron Lycoming Engines, special attention should be given to the transition plus its gaskets and clamps as well as the slip joints for possible crack indications and poor or loose fittings. This service letter is cited in the Mooney M20M Service and Maintenance Manual under Exhaust System Servicing. Several entries of the turbocharger, wastegate, and exhaust were made after December 19, 1990, and were listed in the maintenance record as follows: February 19, 1991; 493 hours TT; turbo, installed Reman wastegate TKR0101 - new gaskets April 9, 1992; 687 hours TT; turbo, wastegate actuator working OK August 11, 1993; 1,001 hours TT; turbo, inspected without removal - appears OK. August 9, 1994, 1,169 hours TT; exhaust; rewelded pipe at #2 and #4 & heat muff; turbo, OK, snug axial/0.005" radial - no wall contact - turns smoothly August 25, 1995, 1,309 hours TT; turbo, replaced with reman turbo; exhaust, piping welded in spots January 24, 1998, 1,546 hours TT, exhaust, rewelded cracks, October 5, 1998, 1,591 hours TT, exhaust, inspected, retorqued & safetied exhaust V-band February 8, 1999, 1,610 hours TT, exhaust, exhaust pipes leaking on right side of engine February 26, 1999, 1,613 hours TT, exhaust, rear exhaust pipe not lining up with rest of pipes - causing burned silicone rubber cabin air intake pipe October 28, 1999, 1,703 hours TT, turbo, housing cracked - installed overhauled turbo October 28, 2000, 1,786 hours TT, wastegate, to exhaust pipe flange cracked - replaced tail pipe November 2, 2001, 1,857 hours TT, turbo, overboosting - valve vane loose on shaft - removed density controller; absolute controller - sent to Main Turbo Systems for repair - installed exchange wastegaste assembly - reinstalled controllers - adjusted to operating specs METEOROLOGICAL INFORMATION The EVV automated surface observing system recorded at 1454: wind 310 degrees at 7 knots; 10 statute mile visibility; clear sky conditions; temperature 10 degrees Celsius (C); dew point 3 degrees C; altimeter setting 30.06 inches of mercury. Visibility and sky conditions values were unchanged for the rest of the day. AIRPORT INFORMATION EVV was served by runway 04-22 (8,021 feet by 150 feet, grooved asphalt), runway 18-36 (3,781 feet by 150 feet, asphalt), and runway 09-27 (3,500 feet by 75 feet, asphalt). WRECKAGE AND IMPACT INFORMATION The main wreckage was resting approximately one mile north of EVV within a 20 foot wide tree line located along residential property. The wreckage path extended through the tree line for 142 feet and a 057 degree magnetic heading. The wreckage path contained sooted and broken branches. The western edge of the wreckage path had a tree about 37 feet in height which exhibited broken branches at the top. The broken branches from this tree towards the main wreckage formed about a 20-degree downward angle. The main wreckage, which consisted of the airframe, engine, and propeller assembly was located at the eastern edge of the wreckage path. The airframe was consumed by fire from the firewall to the remaining empennage which was attached to the tube structure of the airplane. The left horizontal stabilizer and top half of the vertical stabilizer were separated from the empennage and located along the wreckage path. The stabilizer sections were about 51 feet east of the western edge of the wreckage path. The left and right wings both separated from the airframe and separated in several locations along their spans. The engine was resting on its right side and against a tree with the main wreckage. The firewall and instrument panel were crushed on top of the rear accessory area of the engine. All sides of the engine exhibited fire damage. The propeller hub, spinner and two of three propeller blades were separated from the engine and resting about 73 feet northeast of the main wreckage. Both propeller blades were able to be rotated axially by hand. The third propeller blade was located along the wreckage path. All of the propeller blades exhibited bending and twisting. The top spark plugs, magnetos, and engine driven fuel pump were removed and the engine was then rotated by hand at the propeller hub. Engine continuity to the accessory section was confirmed. Thumb compression and suction were also confirmed. The oil suction screen was removed and no contaminant consistent with metal material was noted. The number 1 exhaust pipe remained in its relative position but was separated at the flange. The exhaust pipe was attached to the transition at the crossover. The number 2 exhaust pipe was separated about 2 inches below the flange and separated from the flange and deformed aft. The number 3 exhaust pipe was attached to the cylinder and transition assembly. The number 4 exhaust pipe separated about 8 inches below the exhaust flange. The number 5 exhaust pipe was attached to the cylinder and crossover transition. The number 6 exhaust pipe was attached to the cylinder and separated from the transition. The transition was attached to the wastegate assembly which was attached to the turbocharger. The V-band clamps on either side of the wastegate assembly were attached and had safety wire in place. The turbocharger exhaust pipe was separated at the flange from the turbocharger. The exhaust pipe flange was crushed. The associated V-band clamp was attached at the clamp ends but was separated through its band. There was safety wire in place at the clamp's ends. The fuel selector valve was in the right fuel tank position. The start/magneto switch was past the vertical in the clockwise direction. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy of the pilot was performed by the Vanderbaugh County Coroner, Evansville, Indiana, on November 28, 2001. TESTS AND RESEARCH Radar data and airspeed plots based upon a squawk code of 4521 are included in this report. The separated exhaust clamp was submitted to the National Transportation Safety Board's Material Laboratory for examination. The clamp consisted of a flat band, with fastening hardware, and two inner flange clamps that locate on flanges on the turbo charger housing and the exhaust pipe. Each flange clamp was spot welded to the inner surface on the band at two locations. The fracture of the separated clamp was near the edge a spot weld. Chevron marks on the fracture face indicated that the origin of the fracture was in the region of the spot weld. A photo of the clamp shows the following marking: 677-340M. According to a search of the Federal Aviation Administration’s Service Difficulty Report database yielded 67 occurrences of smoke or fire aboard Mooney airplanes from 1979 to December 5, 2001. A similar search yielded 9 occurrences relating to the exhaust tail pipe clamp on Mooney M20 airplanes from 1984 to 1994. Six of the occurrences occurred from April 10, 1990 to March 1, 1991 and involved the clamp part number 633358 wh
The fatigue failure of the turbocharger exhaust band clamp and aircraft control not possible by the pilot due to the fire.
Source: NTSB Aviation Accident Database
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